greasyfox18

Ok can anyone point me to some pics of the wires i have to jump or what to do to test my cooling fan system....drove it home 140 miles and no fan...but it didnt overheat. But the wont kick on while idling. 2.8 v6

antares57

iTrader: (8)

How high did your engine temp get? The fan normally won't come on until it reaches 220-240. Then it will go off again. If you don't reach these temps, it won't come on. With that in mind you can check your coolant fan relay in the diagram, as well as, your fan switch. If you disconnect the fan switch the fan should run no matter what temp the engine is. You can also apply 12v to the fan and see if it turns with power (last resort). Good luck.

greasyfox18

Thanks i tried the ac method but it didnt work.

greasyfox18

I have two relays on my firewall. Anybody have any actual pics of this stuff dumb it down for me lol

mantaguy

iTrader: (5)

The AC Method only works if the system is charged(Freon)you should have 3 relays on the firewall,Fan,AC,Fuel Pump Relays.

Ozz1967

iTrader: (4)

Run a power wire from the battery (any wire, just needs to get there) to the fan. When
you short this wire to the fan, does the fan turn on?

You also have a switch in the block, just forward of the dipstick. That's the fan switch. Pull the wire from it and ground it to chassis ground.

Turn the car to "Run" without starting it. Does the fan come on?

If the first works, then the fan is good.

If the second works, then the relay and fuseable link are also good. If the second doesn't work, either the relay or the fuseable link are bad.

If the second works, then you have a bad switch.

Also, with the AC check, even without freeon, it should trip the relay to make the fan come on. I'm pretty sure that's an exclusive relay set that doesn't care about the freeon.

Since it doesn't come on, I still want you to do the first parts I mentioned, but..it lends me to think the relay or fuseable link are bad.

greasyfox18

Ok cool thanks ill try it. Got any part numbers for the fuseable link and relay

Ozz1967

iTrader: (4)

Fuseable link you can buy at any autoparts store.

Some switches: *Note, if you buy an except the FS1 (stock temp), you should get a 180* Thermostat as well*
FS6 - Closes at 204*-220* F- Retail $21.59
•FS4 - Closes at 211*-227* F- Retail $8.69
•FS1 - Closes at 222*-238* F- Retail $9.49

For the Relay:
https://www.rockauto.com/catalog/mor...070&cc=1251155

Hope this helps.

I run a 180* Thermostat and a dual fan set up with a two-speed fan. Not something you have to worry about, just showing it for comparison.

Ozz1967

iTrader: (4)

Also, read this thread here:

https://www.thirdgen.org/forums/cool...ernatives.html

It talks about some cars using the ECM and not a switch, however since your's in an 86, I'm 95% sure you use the switch (89 and newer used the ECM). Still, read through and double check.

greasyfox18

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greasyfox18

greasyfox18

I hooked the above wire up from this plug

greasyfox18

And it doesnt work

Ozz1967

iTrader: (4)

I"m not sure what I'm looking at. You didn't narrate all the photos.

The sensor on the drivers side, if that's what that goes to, is to your Temp gauge inside the dash.

On the passenger side is the switch I'm talking about.

I don't know what the black wire with red on it is.

greasyfox18

I thought the cts was on the drivers head behind the ac pump? And the black wire was what i used tog round the wire going into it with.

rdmotors

I had this same problem and years ago I just wired a switch to turn on the relay on the firewall to make the fan run. Got cold in the winter since I had it on all the time. Recently I found out that my eprom was, well cooked, it had a ground fault that messed with all of the electrical in the car. Got a buddy to program a new one and it worked great. The flashers, radio, turn signal and power assc. all seemed to work better and faster. Of course the motor ran better with the dist finally advancing the timing. Rewired the fan relay back to the ecu and it finally turned on and off. So if you can find someone that reprograms eproms for old arcade machines get him to do one for your car and see if that works. The chips suppose to only last 10 years or so. It fixed my problem might get yours also.

greasyfox18

Ok so replaced my relay still nothing. Grounded the temp switch wire nothing.... what next guys? I got the fans to turn on by jumping 12v to the fan

antares57

iTrader: (8)

Did you ground the temp switch located on the driver's side of engine or passenger side of engine? How high of a temp is the coolant temp gauge registering?

greasyfox18

I got an idiot light dash. Grounded the one on the passeger side and drivers side no luck

Ozz1967

iTrader: (4)

Did you make sure the ignition was in "run" when you grounded it? Also, make sure the harness on the back of the relay is pushed up good and tight into the connectors. Mine came "loose" and caused me a week of troubleshooting before I figured it out.

Lastly,

If you were in "run" when you tested the ground, the only thing left in the circuit is the fuseable link. Those things were the supidest invention ever. Anyway, To find it, you'll need to trace the power wire back into the harness from the relay. It looks like a thicker piece of wire hooked inline with the smaller regular wire. One side or the other is probably burned bad. Replace this piece and you should be good to go.

greasyfox18

I have power at the plug for the relay.... i jumped the terminals... thats how i got the fan to work so i k ow thats good.

Ozz1967

iTrader: (4)

Ok that clears some stuff up. That means the fuseable link is good since power is getting through.

Now it can only be, the relay, or the switch.

You said the Fan's do not come on with the AC on? Follow the clutch power wire, it should tie into the fan relay in the harness. With the AC On, your fan should come on. (this is the other method of determining if the fuseable link is good - fans with ac on = good fuseable link).

The issue I'm having is, I'm not entirely familar with V-6 set ups, so I'm making an assumptiong that they're set up basically the same. Drivers side switch is for temp gauge, passenger side switch is for the fan relay.


With the new relay in place, turn the key to turn, take the wire off off the switch in the head, and ground it to chassis ground. What does this do?

greasyfox18

Its doesnt work.

greasyfox18

Someone said that the plug with the yellow and black wires under the throttle body tell the ecm to turn the fan on

greasyfox18

Replaced the sensor and noticed the fans come on when the plug is unplugged.... but nothing when theyre plugged in..... but if i unplug them start it then plug it in they work fine....im so confused

greasyfox18

Someone please help

Ozz1967

iTrader: (4)

Its an improvement! With what you just said, now it sounds like a ground problem somewhere in the circuit. Its possible that some wires are chaffed and are shorting together. It looks like your going to have to start tracing wires.

greasyfox18

Could the computer be bad? Why would the fans work when the sensor is unplugged

Ozz1967

iTrader: (4)

The system works when the ground signal is recieved at the relay from the switch, the ECM doesn't tell it when to turn on or off so I find that theory unlikely. I still think you have a wire loose or chaffed that might be grounded. I mean, we got it to do something where before it wasn't doing anything, so we're going in the right direction.


1. Engine gets to temp, internal sensor in switch (in head) closes, grounding to the switch to the block, sending a signal to the relay.
2. Relay energizes, allowing power through to the fan which turns on. When switch temp cools sufficiently, switch opens, ending ground condition and turning the fans off.
3. With AC, when energized, it sends bypass signal to relay, energizing relay, allowing power through to fan for constant run condition.


That's it. The system is a really simple circuit. We can't be far off from figuring it out.

In 88 and later cars (so far as my research has found anyway), then the ECM controlled the fan's "on" and "off" temperature.

If you need to have this working "right now", you might want to pick up an after market controller to a toggle switch just until you can get the wiring sorted.

willexoIX

Ozz pretty much has it covered, BUT, sensor under the throttle body tells the ecm the coolant temp and thats it. The ecm has NOTHING to do with the fan turning on and off.

As was mentioned, you have a wiring problem. Trace the wire on the fan switch on the passenger side head back to the relay. You will likely find your problem on the way.

Ozz1967

iTrader: (4)

I missed his statment about the Yellow and Black wire. My 84 T/A has this for the CC Qjet, and I think I mentioned it when I talked about a sensor on your manifold, but yes, as Wille says, it's only for the ECM to know when the motor is warm enough and compares that reading with the 02 sensor to adjust the TPS properly. That's it.

mantaguy

iTrader: (5)

The Cooling Fan is Totally controlled buy the ECM

greasyfox18

No luck yet...all looks good in the harness....im still not understanding why when i unplug the censor under the throttle body then start it up it runs but when i shut it off and plug in in they wont run when the engine
Is hot....

mantaguy

iTrader: (5)

Did the temp get to 235 degrees?

Ozz1967

iTrader: (4)

Ok, good find.

Everything I could find, pointed only to 88 and newer being ECM controlled. His is an 86.

So, his earlier statement of his ECM crapping out may very well be accurate in this case since everything else has been checked.

mantaguy

iTrader: (5)

I really think he's not letting it get Hot enough!!He's in PA and it's got to be at least below 0* there.

greasyfox18

So aftermarket fan controller?

mantaguy

iTrader: (5)

Did it get to 235?

greasyfox18

It has to have been at 235 i had it idling for 20 mins and drove around town

mantaguy

iTrader: (5)

Did it Overheat?if not it's fine,did it Boil Over after you shut down?,if not it's fine.

greasyfox18

Didnt do anything smelled very hot though. I just dont like not having fans

Ozz1967

iTrader: (4)

Wow...

Ok. The one thing that bothered me was when he says he turned on the AC, he got no fans. Fans should turn on regardless of outside temp when AC is engaged regardless if the system is charged. It defaults "Fan on" with AC switched on.

What did the temp gauge read when idling/driving around? Does it get in the red?

I definitely understand if the Fans don't work, it making you nervous.

On your trip home, did it get into the red?

mantaguy

iTrader: (5)

I understand,the best thing to do is,pickup a temp.laser light,beings you don't have the gauges.You really should make sure that your car is getting hot enough before you go into all that work chasing down a problem that may or may not exist.

mantaguy

iTrader: (5)

On my 86 if the AC has no Freon it will not kick in the pressure switch that controls the fan.

Ozz1967

iTrader: (4)

Ok. My 84 kicks (V8)the fans on even if I have the AC disconnected physcially and it's only electrically connected. Found that out last summer while Troubleshooting it.

mantaguy

iTrader: (5)

I'm looking through this 86 manual and it's showing the the 2.8 v6 has another fan switch,it's called a redundant fan switch,I don't know if this pertains to your particular engine it's for a vin S.

willexoIX

Is his vin F or vin S? Mine is vin S so there is no control of the fan by the ecm at all on my 89 2.8 RS.

willexoIX

Guess they changed it some year between then and 89. Cause thats the only fan switch on mine.

camarotucker

iTrader: (2)

http://austinthirdgen.org/mkportal/m...ine_wiring.gif

willexoIX

What is your 8th VIN digit?